In Reply: Regional variation in rates of S aureus IE, a concern of Dr Chikamori, almost certainly exists. For example, in the study from the Mayo Clinic1 that accompanied our article, viridans group streptococci were the leading cause of endocarditis in the 102 patients diagnosed with IE from Olmstead County, Minnesota, between 1970 and 2000, whereas investigators in Durham County, North Carolina, reported2 that S aureus was the leading cause of IE seen during much of that same period. The large, multinational, and contemporary design of the ICE-PCS provides us with a unique perspective to address regional variation. We are currently analyzing the data set to address some of these issues. In general, S aureus was the most common cause of IE in most of the geographic regions of the world represented in the ICE-PCS.